A draper assembly for a crop pick-up has an endless draper belt assembly wrapped around a smaller front roller and a larger rear drive roller where the endless draper belt assembly is formed by four endless belts connected side by side at spaced positions along their length for common movement around the rollers. A tracking guide device is defined by a plurality of plastic guide elements mounted in a row on an inside surface of one belt at longitudinally spaced positions along the belt length which cooperates with a groove in the drive roller so that there are least two guide elements in the groove at any point in time. The guide elements are wider than their length and can be fastened through the belt so as to connect to the mounting of some of the fingers on the exterior of the belt.